I must inquire you must inquire he must inquire we must inquire you must inquire they must inquire
V-ing form
I must be inquiring you must be inquiring he must be inquiring we must be inquiring you must be inquiring they must be inquiring
Perfect
I must have inquired you must have inquired he must have inquired we must have inquired you must have inquired they must have inquired
V-ing perfect
I must have been inquiring you must have been inquiring he must have been inquiring we must have been inquiring you must have been inquiring they must have been inquiring
Negation
Simple form
I mustn't inquire you mustn't inquire he mustn't inquire we mustn't inquire you mustn't inquire they mustn't inquire
V-ing form
I mustn't be inquiring you mustn't be inquiring he mustn't be inquiring we mustn't be inquiring you mustn't be inquiring they mustn't be inquiring
Perfect
I mustn't have inquired you mustn't have inquired he mustn't have inquired we mustn't have inquired you mustn't have inquired they mustn't have inquired
V-ing perfect
I mustn't have been inquiring you mustn't have been inquiring he mustn't have been inquiring we mustn't have been inquiring you mustn't have been inquiring they mustn't have been inquiring
Interrogative form
Simple form
must I inquire? must you inquire? must he inquire? must we inquire? must you inquire? must they inquire?
V-ing form
must I be inquiring? must you be inquiring? must he be inquiring? must we be inquiring? must you be inquiring? must they be inquiring?
Perfect
must I have inquired? must you have inquired? must he have inquired? must we have inquired? must you have inquired? must they have inquired?
V-ing perfect
must I have been inquiring? must you have been inquiring? must he have been inquiring? must we have been inquiring? must you have been inquiring? must they have been inquiring?
Interro-negative form
Simple form
mustn't I inquire? mustn't you inquire? mustn't he inquire? mustn't we inquire? mustn't you inquire? mustn't they inquire?
V-ing form
mustn't I be inquiring? mustn't you be inquiring? mustn't he be inquiring? mustn't we be inquiring? mustn't you be inquiring? mustn't they be inquiring?
Perfect
mustn't I have inquired? mustn't you have inquired? mustn't he have inquired? mustn't we have inquired? mustn't you have inquired? mustn't they have inquired?
V-ing perfect
mustn't I have been inquiring? mustn't you have been inquiring? mustn't he have been inquiring? mustn't we have been inquiring? mustn't you have been inquiring? mustn't they have been inquiring?